Electric power outputted from a battery mounted on a vehicle is supplied once, for example, to a main electric wire distributor mounted in an engine room or the like, and is then supplied to a plurality of branch electric wire distributors, which are installed at appropriate spots in the vehicle, through a plurality of main electric wires branched from the main electric wire distributor. Moreover, the electric power supplied to the respective branch electric wire distributors is supplied to a variety of loads such as a motor and a lamp, which are mounted on the vehicle, through the plurality of branch electric wires, and the variety of loads are driven.
Moreover, the main electric wire distributor includes an electronic switch such as a semiconductor switch and a contact-type relay for each of the main electric wires. In the case where an overcurrent is generated in such a main electric wire, the main electric wire distributor shuts off this electronic switch, and thereby protects the main electric wire and an entire circuit on a downstream side thereof from a temperature rise owing to the overcurrent.
In a similar way, each of the branch electric wire distributors includes an electronic switch such as a semiconductor switch for each of the branch electric wires. In the case where an overcurrent is generated in such a branch electric wire owing to a short circuit accident of the load, and the like, the branch electric wire distributor shuts off this electronic switch, and thereby protects the branch electric wire and the load connected to the branch electric wire from a temperature rise owing to the overcurrent.
As a conventional example of an electric power distribution device provided with such an overcurrent protection function, a technology disclosed in PTL 1 has been known. PTL 1 describes such a technology for supplying electric power to a variety of loads mounted in a vehicle in such a manner an output end of a battery mounted on the vehicle is connected to a power supply distributor, further, a plurality of interior power supply distributors are connected to a plurality of main electric wires branched by the power supply distributor, and the loads are connected to a plurality of branch electric wires branched by the respective interior power supply distributors.
Moreover, in the case where an overcurrent is detected in the main electric wire or the branch electric wire, the electronic switches of the power supply distributor and the respective interior power supply distributors are shut off, whereby the entire circuit can be protected from the temperature rise owing to the overcurrent.